Gable top cartons have been known for the better part of the twentieth century. Their characteristic simplicity and resealability have helped to sustain their popularity as containers for traditional liquid food products such as milk and juice, but in recent years they have been used for products ranging from ammunition to Epsom salts. Gable top cartons typically start out as generally rectangular carton blanks made of laminated paperboard or similar material. The carton blanks are provided with a number of creases to facilitate folding and forming the blank into a carton.
During decades of development, manufacturers of packaging machines have devised a variety of ways to form, fill, and seal gable top cartons. Today, the most prevalent packaging machines for gable top cartons are adapted to receive the carton blank after it has been side sealed. The process of side sealing involves sealing opposite vertical edges of the carton blank together to form a polygonal (usually rectangular) sleeve The sleeve is received on an indexable mandrel wheel, which rotates the sleeve into respective positions where the end of the sleeve extending outwardly from the mandrel is folded and sealed to form the bottom of the carton.
After the carton bottom has been formed, the carton is then removed from the mandrel and transported to a filling station, where the carton is filled with product. Once the carton has been filled, the top of the carton is folded and sealed into the familiar gable top configuration, thus completing the packaging process. One example of a known packaging machine that operates generally in accordance with these principles is described in U.S. Pat. No. 3,789,746 to Martensson et al.
Although most gable top cartons appear to be substantially identical, materials and processes vary significantly from manufacturer to manufacturer. One of the principal differences is in the alignment between the uppermost edge ("top fin") and the bottom sea of the carton bottom. Some packaging machines, such as the machine of the Martensson patent, produce gable top containers in which the top fin of the finished container is parallel with the bottom seal. Other machines produce containers such as that shown in U.S. Pat. No. 3,770,185 to Reeves, where the top fin of the finished container is transverse to the bottom seal. As a consequence of this difference, carton blanks must be specifically configured and manufactured for each machine, e.g., the Martensson machine cannot receive blanks such as those shown in the Reeves patent, and a machine that can receive the Reeves blank cannot operate with blanks configured for the Martensson machine.
This incompatibility presents serious problems to product packagers, who often have both types of machines in operation. For example, packagers with several different types of machines are required to purchase carton blanks for each type of machine, usually from different producers. The packager is thus prevented from purchasing blanks in large enough quantities to result in a volume discount, and from diverting blanks from one type of machine to another in the event of machine failure or market changes. As can be seen from the foregoing, the need exists for a solution to the problems of incompatible packaging systems.